JEE Main & Advanced Physics NLM, Friction, Circular Motion JEE PYQ - NLM Friction Circular Motion

  • question_answer
    If a spring of stiffness 'k' is cut into two parts 'A' and 'B' of length \[{{\ell }_{A}}:{{\ell }_{B}}=2:3,\]then the stiffness of spring 'A' is given by:   [AIEEE 11-05-2011]    

    A) \[\frac{3k}{5}\]

    B) \[\frac{2k}{5}\]

    C) \[k\]

    D) \[\frac{5}{2k}\]

    Correct Answer: D

    Solution :

    \[{{\ell }_{A}}=\frac{2\ell }{5},{{\ell }_{B}}=\left( \frac{3\ell }{5} \right)\]
                \[K\ell ={{K}_{A}}{{\ell }_{B}}={{K}_{B}}{{\ell }_{B}}\]
                \[K\ell ={{K}_{A}}\left( \frac{2\ell }{5} \right)\]
    \[\Rightarrow \]\[{{K}_{B}}=\frac{5K}{3}.\]

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